Abstract: A liquid treatment installation comprises apparatus for controllably treating a liquid with a liquid treatment substance. The apparatus comprises a body, a container for a liquid treatment substance in the body, and a removable closure member on the body. The installation also includes a liquid supply conduit connected to the liquid inlet of the apparatus, a liquid discharge conduit connected to the liquid outlet of the apparatus, and level control means for maintaining the liquid level in the container, thereby to dose liquid passing through the body accurately with liquid treatment substance.

Abstract: A water resistant corrugated paperboard material is prepared wherein the paperboard components (medium and liner or liners) are each coated on both sides with a thermoplastic film which acts as a water barrier and a water resistant adhesive for bonding the components together. The corrugated medium is also pretreated with an internal size treatment to prevent edge wicking, and, for the purpose of corrugating the medium without deleteriously affecting the thermoplastic film, the corrugating rolls are preheated to a temperature slightly less than the melting point of the thermoplastic film while a lubricating material is simultaneously applied to either the corrugating rolls or the medium at the corrugating nip.